K3: in-band-IMD etc. what does this mean to a user?

[DOUGLAS ZWIEBEL]

Hi,

These are pretty graphs and it's nice to see some folks who actually
can discuss this, but what does this mean in practical terms?
Empirically, what will I notice when using the radio?

Thanks,
de Doug KR2Q
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[Ignacy]

Once I started a thread on eham on Mark V Field having high AF distortion; the second harmonic of a 400Hz carrier was only about 30 db below. After many exchanges it turned out that I was overdriving the sound card; after reducing the input the second harmonic was about 45 db below, not bad.

45 db is what they are finding. Not bad.

Ignacy, NO9E

 

[.k8dd.-2]

And if you want to record your TX and RX audio it is very possible to
overdrive the sound card because the Line Out level is controlled by the AF
Gain control!

73    Hank    K8DD



----- Original Message -----
From: "Ignacy" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, November 12, 2008 10:18 PM
Subject: Re: [Elecraft] K3: in-band-IMD etc. what does this mean to a user?

>
> Once I started a thread on eham on Mark V Field having high AF distortion;
> the second harmonic of a 400Hz carrier was only about 30 db below. After
> many exchanges it turned out that I was overdriving the sound card; after
> reducing the input the second harmonic was about 45 db below, not bad.
>
> 45 db is what they are finding. Not bad.
>
> Ignacy, NO9E
>

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[Geoffrey Mackenzie-Kennedy]

Fair enough, but if the sound card was being overdriven in their *two tone*
tests, the same IMD products should appear in the two tone test trsults from
all four types of receiver which is not the case. This assumes of course
that the input levels to the sound card are the same plus minus a little
during each test.

73,
Geoff
GM4ESD

----- Original Message -----
From: "hank k8dd" <[hidden email]>
To: "Ignacy" <[hidden email]>; <[hidden email]>
Sent: Thursday, November 13, 2008 5:07 AM
Subject: Re: [Elecraft] K3: in-band-IMD etc. what does this mean to a user?


And if you want to record your TX and RX audio it is very possible to
overdrive the sound card because the Line Out level is controlled by the AF
Gain control!

73    Hank    K8DD



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